1. Field of the Invention
The present invention relates to a sewing machine capable of forming a stitch pattern, and more particularly to a sewing machine having a pattern indicating function.
2. Discussion of the Related Art
Zigzag sewing machines capable of forming stitch patterns are generally known. Such zigzag sewing machines incorporate a needle bar having a needle, which is rocked at a desired angle, and give a desired feeding motion to a work fabric on a bed by a feed dog extending from a throat plate so as to be movable upward/downward and forward/backward, thereby sewing various stitch patterns, such as letters and figures. In recent zigzag sewing machines, a microcomputer is included in a control unit to electrically control the motions of the needle bar and the feed dog, so that many stitch patterns may be easily sewn. In the case of sewing stitch patterns such as alphabetical letters and edgings on the work fabric, data relating to these stitch patterns are preliminarily stored in a memory such as ROM in a control circuit, and the motions of the needle bar and the feed dog are given under control according to the pattern data selectively read from the memory by a microprocessor (CPU), thereby easily sewing the stitch patterns on the work fabric.
In this kind of a computer controlled sewing machine, a display device such as a liquid crystal display capable of displaying patterns is normally included so that an operator may directly visibly confirm what kinds of patterns are stored in the memory and which pattern has been selected.
In the case of selecting a desired pattern from the memory and sewing a stitch pattern corresponding to the selected pattern on the work fabric, the operator must decide a start position of sewing on the work fabric placed on the bed before starting the sewing. However, the decision of the start position of sewing is very hard especially for a beginner, and it is sometimes necessary for him to re-try the decision in the course of sewing. Thus, the decision of the start position of sewing is a bottleneck in the operation.
Some of the recent zigzag sewing machines which are commercially available include a mechanism for laterally feeding the feed dog, so as to sew a stitch pattern having a larger size. In association with this, it is frequently carried out, for example, to sew a large frame pattern on the work fabric and thereafter sew a letter indicative of a message. In this case, a sewing position of the letter must be precisely set so that the frame pattern previously sewn does not interfere with the letter to be sewn later. However, this operation is generally hard for the beginner, and it is often necessary for him to re-try the operation.
These inconveniences are caused by the fact that it is generally hard for the operator to perceive an actual size and direction of the stitch pattern corresponding to the selected pattern to be sewn on the work fabric and a start position of sewing of the stitch pattern on the work fabric. To cope with this problem, it is known to provide means for numerically displaying a width of oscillation of the needle, a length of a stitch, etc. on a liquid crystal display, so that the operator may perceive how largely the selected pattern is to be sewn as the stitch pattern.
However, even by numerically displaying the width of oscillation of the needle and the length of the stitch on the display, a sewing position of the stitch pattern on the work fabric cannot be precisely confirmed. Accordingly, in order to precisely sew the stitch pattern at a desired position, the operator must manually rotate a pulley of the sewing machine to confirm a position of needle location or carry out trial sewing. Thus, there still remains such a troublesome problem.